Empenthrin

Description

Empenthrin, also known as vaporthrin, (2E)-1-ethynyl-2-methyl-2-penten-1-yl 2,2- dimethyl-3-(2-methyl-1-propen-1-yl) cyclopropanecarboxylate, is a derivative of 1-ethynyl- 2-methyl penten-2-ol. The vapor pressure of empenthrin at room temperature is suitable and therefore it has a natural volatility. At 30 °C, the vapor pressures of empenthrin and allethrin are 1.62?×?10?3 and 1.20?×?10?4 mmHg, respectively. Thus, the vapor pressure of empenthrin is about 10 times more than that of allethrin. Moreover, empenthrin is odorless. It has strong killing activity and repellent effect on pests and is very suitable for textile mothproofing.

Chemical properties

Empenthrin is a light yellow and oily liquid with a boiling point of 346°C and a flash point of 144°C. Its density is 0.999 g.cm^–3 at 20°C. The refractive index of empenthrin is 1.5270 at 20°C. It has low acute mammalian toxicity (its oral LD50 is >5,000 mg.kg^–1 in male rats, >3,500 mg.kg^–1 in female rats and >3,500 mg.kg^–1 in mice). It is, however, very toxic to fish and other aquatic organisms.

The Uses of Empenthrin

Empenthrin is used as a domestic insecticide, especially against moths and other insects which attack fabrics.

The Uses of Empenthrin

Empenthrin is an insecticidal pyrethroid compound.

What are the applications of Application

Empenthrin is an insecticidal pyrethroid compound

Definition

ChEBI: Empenthrin is a monoterpenoid.

Preparation

About 3.72 g (0.03 mol) of 2-methyl-1-ethynyl-2-pentenol and 3.16 g (0.04 mol) of pyridine were added to toluene to form a solution. A toluene solution containing 5.6 g (0.03 mol) of Chrysanthemoyl chloride was added in a dropwise manner. The reaction was carried out at a temperature of 40–50°C for 6h. After reaction, the reaction solution was washed with water until neutral, dried and then subjected to distillation under reduced pressure. About 5.7 g of empenthrin was collected from a fraction of 120–126°C (0.03 mmHg). The yield of empenthrin was 69%.

Metabolic pathway

Empenthrin is a low molecular weight ester of (1R)-chrysanthemic acid (2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylic acid). It has a relatively high vapour pressure and, unlike most pyrethroids, it is effective against flying insects. The molecule has three chiral centres and geometric isomerism in the alcohol group but, with the exception of the 1R acid, the full isomer mixture is used. As the insecticide has been developed for domestic use, it is unlikely that there will be a requirement for metabolism studies in plants or for extensive environmental fate studies. Its metabolism in rats has been reported, with particular attention paid to the fate of the novel alcohol moiety. As with other pyrethroids, ester cleavage and oxidation and conjugation of the alcohol metabolite predominated. The fate of the chrysanthemic acids can be assessed by reference to phenothrin.

Degradation

Empenthrin is a stable molecule but it would be expected to be labile at pH values above 10.